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(No Model.)

E T. GILLILAND. TELEPHONE RECEIVER.

No. 356,197. Patehted Jan. 18, 1887.

times STATES PATENT OFFICE.

EZRA r. GILLILAND, on NEW YORK, N. Y.

TELEPHONE-RECEIVER.

SPECIFICATION forming part vof Letters Patent No. 356,197, dated January 18, 1887.

Application fill d August 2, 1886. Serial No. 209,744. (No modehl To all whom z'tmcty concern):

Be it known that I, EZRA T. GILLILAND, of the city of New York, in the county and State of New York, have invented a certain new and useful Improvement in Telephone-Receivers,

of which the followingis a specification.

My invention relates principally to telephone-receivers intended especially for use in systems of railway-signaling, such as are set forth in'prior applications of Thomas A. Edison and myself-that is, to a system in which signals are communicated from the telegraphwires by induction to the moving car, the receiving-instruments in the car being in connection with an induction-surface upon the car. The signal-receiving instrument which it is preferred to employ is a magneto-telephone receiver, whose diaphragm is thrown into musical vibrations to produce audible Morse signals by the induction-impulses which are controlled by a suitable vibrating transmitter. The currents employed in ordinary telegraph-work do-not effect. such receivers by induction, so as to interfere with the railwaysignals; but it has been found that when the telegraph-wires are conveying the very powerful currents used for quadruplex telegraphy such currents often communicateiuduction-impulses which act with so much greater force on thetelephone-diaphragm that they produce vibrations sufficientto drown the musical signal-vibrati0ns, so that the latter cannot be distinguished or understood.

The object of my invention is mainly to so construct a magneto-telephone receiver as to overcome this difficulty; and my invention principally consists in the novel devices and combinations of devices employed by me in accomplishing this object, as hereinafter described and claimed.

The invention is illustrated in the accompanying drawing, which is a View of a telephone-receiver, partly in section and partly in elevation, embodying said invention.

A is the case.

B is the permanent magnet, and G is the coil wound upon a spool, D.

E is a diaphragm, which may be a thin plate of metal, or may be composed of mica or other is not secured at its edges, but is held directly upon the end of the magnet B by a spring, a, which extends from the case, and has a downwardly-extending point or projectiomb, which rests upon the center of the diaphragm over the center of the magnet-pole. I find that when the center of the diaphragm is thus held against the magnet the most powerful impulses do not affect the diaphragm so as to obscure the ordinary signaling-impulses. The reason of this may be that as the diaphragm can have only a very slight or infinitesimal movement at any time, the strongest impulses cannot have any practically greater effect upon it than the weaker ones, and the musical tones of the railway-signals can always be distinguished from the sound produced by the quadrupleX-telegraph or other powerful currents. Since only very small vibrations are necessary for the signals, these are not prac tically impaired by the holding of the diaphragm at its center.

Since the diaphragm does not close the mouth of the receiver, when the instrument is held against the car a roaring sound will be produced, as is the case with any hollow body closed at its outer and open at its inner end. To remedy this I prefer to close the receiver by a plate, G, through the center of which the magnet passes. Preferably, this plate is made in one piece with the spool D, the head of the spool being enlarged so as to fit the case. As shown, plate G rests upon a shoulder on the case, and the ear-piece H is screwed upon the end of the case and rests upon the plate to secure it. Plate G may, however, be a separate disk having a central aperture and set upon the head of the spool. The plate has a notch or aperture, 0, through which the spring it passes.

It is evident that this device is adapted to any telephoncreceiver in which the diaphragm is free at its edges, so as not to close the hollow case. 7

Instead of closing the outer end of the chamber, I may open the other end by means of apertures d d, (shown in dotted lines,)extending through the head of the case. This permits a circulation of air, and thus also prevents the suitable insulatingmaterial. This diaphragm roaring sound referred to.

What I claim is- 1. In a telephone-receiver, the combination, with the magnet, of the diaphragm free at its edges and held by spring-pressure against the end of said magnet, substantially as set forth.

2. In a telephone-receiver, the combination, with a magnet, of a diaphragm held against said magnet by an external spring, substan tially as set forth. 7

3. In a telephone-receiver, the combination of a magnet, a diaphragm resting upon the end of said magnet and free at its edges,and a spring-point pressing upon the cent-er of said diaphragm, substantially as set forth.

I, 4. In a telephone-receiver, the combination of a magnet, a diaphragm resting upon the end of said magnet and free at its edges, and aflat spring secured to the case and provided with a point or projection pressing upon the center of said diaphragm, substantially as set forth.

5. In a telephone-receiver, the combination, with a hollow case and a diaphragm free at its edges, of a plate closing the mouth of said case, substantially as set forth.

6. In a telephone receiver, the combination 

